CN101821902B - System and method for improving antenna isolation using coupling elements - Google Patents

Abstract

An antenna system includes a first antenna element mutually coupled to a second antenna element, the mutual coupling between the first and second antenna elements causing a first current to be generated in the second antenna element, and a coupling element positioned at least partially between the first and second antenna elements, wherein the coupling element is mutually coupled to the first and second antenna elements, and the coupling element is configured to generate a second current in the second antenna element that at least partially cancels the first current.

Description

Adopt coupling element to improve the system and method for antenna isolation

Technical field

The present invention relates generally to antenna with multiple radiators, particularly adopt component to reduce the system and method for mutual coupling between a plurality of antenna elements (mutual coupling) influence.

Background of invention

Along with antenna system becomes more and more littler, become not enough more in the space between the antenna element in these systems.Space between the antenna element not only possibly influence the radiation pattern of system, and possibly influence the mutual coupling between the antenna element.Mutual coupling is the inductance/capacitance coupling between two or more antennas, sometimes maybe be because the performance degradation that disturbs the signal launched or cause because making the antenna element unnecessary signal of emission being harmful to.Usually, the position of two antenna elements is near more, and the possibility of mutual coupling is just high more.

So, modern antenna design person usually all finding method reduce between the antenna element coupling (isolating) as improving.Particularly to multichannel system, because the signal on a channel is not influenced by the signal on other channel should or can in theory.Equally, also be to need to reduce coupling for multiple-input and multiple-output (MIMO) antenna system especially, MIMO requires some antennas on same frequency, to move, but separate work.

Some antenna systems take antenna element to place the ground plane top.In such system, antenna element can produce electric current on ground plane, and it flows to other antenna element, increases unwanted coupling.In order to reduce coupling, various technical methods have been proposed.For example, a solution is to separate ground plane, makes two antennas of possibility phase mutual interference connect through a continuous ground plane.But this system does not produce enough isolation usually.

The system of other proposition comprises that complicated manufacture process comes the generation unit structure, and the unit is shorted to ground through the via hole on the printed circuit board (PCB) (PCB).This similar is served as band stop filter (bandstop filter) usually in photon band gap (PBG is used for optical field) structure, can design to delete some unwanted signal.But this system is because its complicated three-dimensional structure shape seems very expensive.At present, prior art systems can provide enough isolation in the absence of minimal complexity.

Summary of the invention

Various embodiment of the present invention relates to the system and method that in the antenna with multiple radiators system, comprises a coupling element.In an example, coupling element is placed between two antenna elements.The shaped design of coupling element becomes, and makes it can offset the electric current that the direct coupling owing to element produces.In some embodiment, coupling element can be very little, thereby space economy property is provided.And, the be far from complex design of PBG of various embodiment, therefore the manufacturing cost than the prior art systems of use PBG isolated component is more cheap.

Aforementioned characteristic of the present invention and the technical advantage set forth quite widely is so that can understand detailed description of the present invention subsequently better.Further feature of the present invention and advantage will be in following descriptions, and it constitutes claim of the present invention.It should be appreciated by those skilled in the art that and to utilize notion disclosed here and specific embodiment easily, and be used for revising or designing other structure being used for carrying out the identical purpose of the present invention as a basis.Those skilled in the art should be appreciated that also this equivalent constructions does not break away from the spirit and scope of the present invention of in accessory claim, setting forth.No matter be counted as the novel features of characteristic of the present invention, be its tissue and method of operation, with other purpose and advantage, from following description and combine accompanying drawing to be better understood.But, should profoundly understand, each accompanying drawing that provides only is as describing and illustrative purposes, is not to be intended to as restriction definition of the present invention.

Description of drawings

In order to understand the present invention more all sidedly, combine accompanying drawing that reference is made in following description at present, wherein:

Fig. 1 describes the exemplary antenna system of one embodiment of the invention;

Fig. 2 describes the exemplary antenna system of one embodiment of the invention;

Fig. 3 describes the canonical system of one embodiment of the invention;

Fig. 4 describes the canonical system of one embodiment of the invention;

Fig. 5 describes the canonical system of one embodiment of the invention;

Fig. 6 shows the typical antenna array of the embodiment of the invention;

Fig. 7 describes the typical USB Dao Er chip of one embodiment of the invention; With

Fig. 8 describes the typical method of one embodiment of the invention.

Detailed Description Of The Invention

Fig. 1 describes theexemplary antenna system 100 of one embodiment of theinvention.System 100 comprisesantenna element 101 and 102, and coupling element 103.In this example,antenna element 101 is driven by a radio frequency (RF) feed, and the electric current that antenna element is 101 li is I_Excited102 li of antenna elements, because the total current that causes withantenna element 101 mutual coupling is I_Coupled

Three zones are arranged in Fig. 1.Zone 110 is not zones betweenantenna element 101 and 102 of coupling element 103.In other words, inzone 110, eachantenna element 101 and 102 is all in the sight line ofanother element.Zone 120 is similar to zone 110.Inzone 130,coupling element 103 is betweenantenna element 101 and 102.

Inzone 110 and 120, direct coupling (direct coupling) is arranged betweenantenna element 101 and 102.In this example, the electric current that is caused by direct coupling is I_Direct, it equals α I_Excited, wherein α is a constant, receives distance andzone 110 and 120 size impact betweenantenna element 101 and 102.I_DirectWith I_Excited(for example, out-phase is 180 °) in theopposite direction.In zone 130, the coupling betweenantenna element 101 and 102 is not direct.On the contrary, inzone 130,antenna element 101 and 102 is coupled rather than coupling mutually withcoupling element 103 separately.Antenna element 101 andcoupling element 103 couplings, thus an electric current oncoupling element 103, produced, with I_DirectIn the opposite direction.Then, at the induced current on thecoupling element 103 an electric current (I who onantenna element 102, produces is arranged_Cancel), be inverted about 180 ° once more.I_CancelPhase place and I_DirectPhase directional opposite, I_CancelCan be expressed as β I_Excited, wherein β is a constant, its depend onantenna element 101 and 102 andcoupling element 103 between distance and the size of coupling element 103.In this example, β is approximately equal to α, thus I_Coupled=I_Direct+ I_Cancel～0.

In this example,antenna element 101 and 102 is shown as dipole element, and its length is λ/2 normally.The total length ofcoupling element 103 comprises vertical and horizontal component, also is λ/2.Constant β receives the effect length of the vertical component (for example, parallel with 102 with antenna element 101) of coupling element 103.The horizontal component of coupling element 103 (for example, vertical with 102 with antenna element 101) is very little to the influence of β.On the contrary, the existence of horizontal component is to make that the total length ofcoupling element 103 is λ/2.

Although above example relates to level and vertical component, these vocabulary only are for ease of describing.Usually can say so, the part with the coupling element (for example, 103) of its adjacent antenna element (for example, 101 and 102) mutual coupling can influence β, still, with the part of its not mutual coupling of adjacent antenna element be to be used for guaranteeing that total length is a resonance length.

Fig. 2 describes theexemplary antenna system 200 of one embodiment of the invention.Fig. 2 shows an antenna System Design that size (millimeter) arranged above that, and also offer curves Figure 25 0 and 260 explains the performance ofantenna system 200.

Antenna system 200 is built on the printed circuit board (PCB) (PCB) 205, and it comprisesantenna element 201 and 202,coupling element 203 and ground plane 204.Obvious from Fig. 2,antenna element 201 and 202 is planar inverted F-shape antenna (PIFA) elements.Because they are contiguous each other,antenna element 201 and 202 mutualcoupling.Coupling element 203 reduces or reduces the mutual coupling influence, thereby improves the performance ofantenna system 200.

Though the example of Fig. 1 has shown a coupling element that total length is λ/2, not all embodiment is so limited.In the embodiment that uses resonance length as the antenna element of λ/4, the total length of coupling element also is λ/4.The example that has resonance length and be the antenna element of λ/4 comprises such as monopole (monopole) and PIFA.Using in the example of PIFA as theantenna system 200 ofantenna element 201 and 202,coupling element 203 has the length of λ/4.

Curve chart 250 shows that one is similar toantenna system 200 but does not have the emulation and the measurement performance of the antenna system of coupling element 203.On the contrary, the emulation and the assessment result ofcurve chart 260 display systems 200.Oncurve chart 250, have at the 2.45GHz place-coupling of8dB.Curve chart 260 is presented at the coupling of 2.45GHz place-30dB, and expression has and surpasses-improvement that 20dB isolates.Consider-30dB means only has a unit coupling to each thousand energy unit, and this improvement is impressive.To the system of real world, be difficult to realize zero coupling, still, the embodiment of the invention can be improved isolation, makes coupling effect near zero (shown in thecurve chart 260).In many systems, the mutual coupling effect of reduction-20dB can be reduced to one with coupling effect influences negligible grade to systematic function.

Fig. 2 shows that the coupling length (not being total length) ofcoupling element 203 is two millimeters.When the designing antenna system, can adjust coupling length to pass through influencing β and the tuning system performance.In fact, can emulation and/or the test different length to reach an optimization length.

Though size is provided in Fig. 2, and the present invention is not so limited.Can use any various design and structure, each system can be moved on special frequency band by allotment, and adopts different sizes.In fact, the virtually any size that in specification, provides only is as description, rather than as restriction of the present invention.

System 200 exists direction diversity (directional diversity), whereinantenna element 201 and 202 radiation in different directions.Because in the diversity of 200 li of antenna systems,antenna system 200 goes for MIMO and uses.Coupling element 203 between theantenna element 201 and 202 is the performance of enhanceantenna system 200 through the coupling effect between the different resonant elements of reduction.

Fig. 3 describes thecanonical system 300 of one embodiment of the invention.Various embodiments of the invention comprise three-dimensional (3D) structure, the embodiment shown insystem 300.

System 300 comprises dipoleaerial element 301 and 302 and coupling element 303.Antenna system 300 is designed on the frequency band about 2.4GHz performance is provided.Curve chart 310 shows the simulation result that hascoupling element 303 and do not have theantenna system 300 of coupling element 303.Can see that from figure the appearance ofcoupling element 303 increases the isolation around system's 300 resonance frequencys.

Some embodiment may be implemented within the multiband application.Fig. 4 describes thecanonical system 400 of one embodiment of theinvention.System 400 is MIMO antennas, and it provides performance on 2.4GHz and5GHz.System 400 build on the PCB405, comprisesPIFA element 401 and 402,coupling element 403 and ground plane 404.Coupling element 403 comprises two coupling units: a part comprises 403a and 403c, and another part comprises 403b and 403c.Eachcoupling unit 403a adds 403c and 403b and adds 403c a different coupling length (like different β) and a different effective total length are arranged, thereby provides a different operation frequency band to add 403c to eachcoupling unit 403a and 403b adds 403c.In this example,coupling element 403 provides isolation toantenna system 400 on 2.4GHz and 5GHz.

The embodiment ofsystem 400 can approximately be the such size of a flash memory " memory stick ", and is included in a USB (USB) the Dao Er chip, like the typical Dao Erchip 700 of Fig. 7.In fact,system 400 can be connected to a computer through a USB interface, connects so that WLAN (LAN) to be provided.

The number of antenna element and coupling element can be used in the special application in proportion.Fig. 5 describes thecanonical system 500 of one embodiment of theinvention.System 500 comprises antenna element 501-504 and coupling element 511-514.Coupling element 511 provides isolation betweenantenna element 501 and 502, similarly,coupling element 513 provides isolation betweenantenna element 503 and 504.Coupling element 512 and 514 provides isolation respectively betweenantenna element 502 and 503 and 501 and 504.

The embodiment of the invention goes for the various antenna systems of any kind.For example, embodiment goes for adopting in the system of ground connection or earth-free antenna element of dipole, one pole, PIFA and any other type.And various embodiment go for many different arrays, like 2D, 2.5D and 3D array.Fig. 6 shows the typical antenna array 610,620,630,640 and 650 of the embodiment of the invention.Coupling element, those elements as shown in above Fig. 1-5 can be used between Fig. 6 array internal antenna element, increase and isolate.

Various embodiment of the present invention uses coupling element to increase isolation.Fig. 8 describes thetypical method 800 of one embodiment of theinvention.Method 800 can be carried out on like described embodiment in above Fig. 1-7.

Ataction 801, excitation first electric current on first antenna element.In an example, first antenna element is by a radio frequency (RF) module drive.Electric current can be on any RF frequency band, comprises the frequency band of use in WiFi (IEEE801.11) application, cellular phone application and other RF use, and lists in this inconvenient total number.

Directly bring out generation second electric current on second antenna element ataction 802, the first electric currents.First electric current directly produces an example such as the description of above relevant Fig. 1, the wherein I of second electric current_ExcitedProduce I_Direct

Produce by first current induced on the coupling element ataction 803, the threeelectric currents.At action 804, the four electric currents is to be created on second antenna element by the 3rd electric current.The 4th electric current and second electric current are out-phase, reduce the mutual coupling effect between first and second antenna elements through offsetting second electric current at least in part.

Thoughmethod 800 shows to have a series of discrete step, various embodiment of the present invention are not so limited.Some embodiment can increase, revise, rearrange and/or ignore wherein one or more actions.For example, from the mankind's angle, the 801-804 that seems to move is simultaneous, and continues to take place at the antenna system run duration.In addition, other method possibly comprise this characteristic, as offsets the mutual coupling effect on two or more frequency bands, the mutual coupling effect between the more than a pair of antenna element of counteracting etc.

Various embodiment of the present invention has the advantage that surmounts the prior art solution.For example, the solution of PBG is complicated, expensive and huge.On the contrary, coupling element, those elements as previously discussed, comparing with the solution of PBG is quite simple structure.And, when with PCB on metal one time-out, to a given antenna system, coupling element only increase seldom or do not increase extra manufacturing cost.

Though specified the present invention and superiority thereof, should be understood that under the condition of the present invention that does not break away from the accompanying claims definition and can make various changes, replacement and variation.In addition, the application's scope is not limited to the processing method of describing in the specification here, and machine is made, and material constitutes, means, the specific embodiment of method and step etc.Can understand easily from specification, can utilize carried out in fact with here the explanation corresponding embodiment identical function or realized the present existing of identical result or the processing method of developing in the future, machine; Make; Material constitutes, means, method and step.Therefore, appending claims is intended to comprise these processing methods, and machine is made, and material constitutes, means, method or step.

Claims (20)

Translated fromChinese

1.一个天线系统，包括：1. An antenna system comprising:第一天线元件；a first antenna element;第二天线元件，其中电磁耦合发生在第一天线元件和第二天线元件之间，使得第一元件上的电流I_Excite产生电流I_Direct在第二天线元件上；和a second antenna element, wherein electromagnetic coupling occurs between the first antenna element and the second antenna element such that a current I_Excite on the first element produces a current I_Direct on the second antenna element; and一个耦合元件，位于第一和第二天线元件之间，并与第一和第二天线元件互耦，使得耦合元件产生电流I_Cancel，且其中I_Cancel至少部分抵消I_Direct，其中I_Cancel为βI_Excite，β是一个常数，其取决于第一和第二天线元件以及耦合元件之间的距离以及耦合元件的尺寸，a coupling element positioned between and mutually coupled to the first and second antenna elements such that the coupling element generates a current I_Cancel , and wherein I_Cancel at least partially cancels I_Direct , where I_Cancel is βI_Excite , β is a constant that depends on the distance between the first and second antenna elements and the coupling element and the size of the coupling element,所述耦合元件包括一个与第一和第二天线元件互耦的部分和一个与第一和第二天线元件不互耦的部分，与第一和第二天线元件互耦的部分影响β，而与第一和第二天线元件不互耦的部分是用来确保总耦合元件的长度是一个谐振长度。The coupling element includes a portion that is mutually coupled to the first and second antenna elements and a portion that is not mutually coupled to the first and second antenna elements, the portion that is mutually coupled to the first and second antenna elements affects β, and The portion that is not mutually coupled with the first and second antenna elements is used to ensure that the total coupling element length is a resonant length.2.根据权利要求1所述的天线系统，其中在第二天线元件上的总耦合电流是I_Couple，其中I_Couple等于I_Direct加上I_Cancel，且I_Couple是可以忽略的。2. The antenna system of claim 1, wherein the total coupling current on the second antenna element is_ICouple , where_ICouple is equal to_IDirect plus_ICancel , and_ICouple is negligible.3.根据权利要求2所述的天线系统，其中I_Couple近似为零。3. The antenna system of claim 2, wherein_ICouple is approximately zero.4.根据权利要求2所述的天线系统，其中I_Cancel抵消I_Direct至少-10dB。4. The antenna system of claim 2, wherein I_Cancel cancels I_Direct by at least -10 dB.5.根据权利要求1所述的天线系统，其中所述耦合元件包括与所述第一和第二天线元件平行的一部分和与所述第一和第二天线元件垂直的一部分。5. The antenna system of claim 1, wherein the coupling element includes a portion parallel to the first and second antenna elements and a portion perpendicular to the first and second antenna elements.6.根据权利要求5所述的天线系统，其中所述平行部分的尺寸被设计用来产生I_Cancel。6. The antenna system according to claim 5, wherein the dimensions of the parallel section are designed to produce I_Cancel .7.根据权利要求5所述的天线系统，其中所述第一和第二天线元件包括偶极元件，其中所述垂直部分和所述平行部分的总长度是λ/2。7. The antenna system of claim 5, wherein the first and second antenna elements comprise dipole elements, wherein the total length of the vertical portion and the parallel portion is λ/2.8.根据权利要求5所述的天线系统，其中所述第一和第二天线元件包括平面倒F型天线（PIFA）元件，其中所述垂直部分和所述平行部分的总长度是λ/4。8. The antenna system of claim 5, wherein the first and second antenna elements comprise planar inverted-F antenna (PIFA) elements, wherein the total length of the vertical portion and the parallel portion is λ/4 .9.根据权利要求1所述的天线系统，其中所述天线系统在多个单一频带上提供性能，其中所述耦合元件在所述多个单一频带上提供隔离。9. The antenna system of claim 1, wherein the antenna system provides performance over a plurality of single frequency bands, wherein the coupling element provides isolation over the plurality of single frequency bands.10.一种在天线系统里增加隔离的方法，其中天线系统包括第一天线元件、第二天线元件和耦合元件，所述方法包括：10. A method of increasing isolation in an antenna system, wherein the antenna system includes a first antenna element, a second antenna element and a coupling element, the method comprising:在所述第一天线元件上励磁第一电流I_Excite；Exciting a first current I_Excite on said first antenna element;由所述第一电流I_Excite直接诱发产生第二电流I_Direct在所述第二天线元件上；directly induced by the first current I_Excite to generate a second current I_Direct on the second antenna element;由所述第一电流I_Excite产生第三电流在所述耦合元件里；和generating a third current in said coupling element from said first current I_Excite ; and由所述第三电流产生第四电流I_Cancel在所述第二天线元件里，所述第四电流I_Cancel与所述第二电流I_Direct是异相的，并降低所述第一和第二天线元件之间的互耦效应，其中I_Cancel为βI_Excite，β是一个常数，其取决于第一和第二天线元件以及耦合元件之间的距离以及耦合元件的尺寸，A fourth current I_Cancel is generated from the third current in the second antenna element, the fourth current I_Cancel is out of phase with the second current I_Direct and reduces the first and second Mutual coupling effect between antenna elements, where I_Cancel is βI_Excite , β is a constant, which depends on the first and second antenna elements and the distance between the coupling elements and the size of the coupling elements,所述耦合元件包括一个与第一和第二天线元件互耦的部分和一个与第一和第二天线元件不互耦的部分，与第一和第二天线元件互耦的部分影响β，而与第一和第二天线元件不互耦的部分是用来确保总耦合元件的长度是一个谐振长度。The coupling element includes a portion that is mutually coupled to the first and second antenna elements and a portion that is not mutually coupled to the first and second antenna elements, the portion that is mutually coupled to the first and second antenna elements affects β, and The portion that is not mutually coupled with the first and second antenna elements is used to ensure that the total coupling element length is a resonant length.11.根据权利要求10所述的方法，其中天线系统里所述第一和第二天线元件之间的所述互耦被降低到可以忽略。11. The method of claim 10, wherein said mutual coupling between said first and second antenna elements in an antenna system is reduced to negligible.12.根据权利要求10所述的方法，其中所述第一和第二天线元件之间的所述互耦被降低至少-10dB。12. The method of claim 10, wherein the mutual coupling between the first and second antenna elements is reduced by at least -10 dB.13.根据权利要求12所述的方法，其中所述第一和第二天线元件之间的所述互耦被降低至少-20dB。13. The method of claim 12, wherein the mutual coupling between the first and second antenna elements is reduced by at least -20 dB.14.一个天线系统，包括：14. An antenna system comprising:第一天线元件，与第二天线元件互耦，所述第一和第二天线元件之间的所述互耦由第一天线元件上的电流I_Excite产生第一电流I_Direct在所述第二天线元件上；和The first antenna element is mutually coupled with the second antenna element, and the mutual coupling between the first and second antenna elements is caused by the current I_Excite on the first antenna element to generate a first current I_Direct in the second antenna element. on the antenna element; and一个耦合元件，至少部分地位于所述第一和第二天线元件之间，所述耦合元件与所述第一和第二天线元件互耦；a coupling element positioned at least partially between said first and second antenna elements, said coupling element being mutually coupled with said first and second antenna elements;所述耦合元件被设置以产生第二电流I_Cancel在所述第二天线元件上，其至少部分抵消所述第一电流I_Direct，其中I_Cancel为βI_Excited，β是一个常数，其取决于第一和第二天线元件以及耦合元件之间的距离以及耦合元件的尺寸，The coupling element is arranged to generate a second current I_Cancel across the second antenna element which at least partly cancels the first current I_Direct , where I_Cancel is βI_Excited , β being a constant which depends on the first the distance between the first and second antenna elements and the coupling element and the dimensions of the coupling element,所述耦合元件包括一个与第一和第二天线元件互耦的部分和一个与第一和第二天线元件不互耦的部分，与第一和第二天线元件互耦的部分影响β，而与第一和第二天线元件不互耦的部分是用来确保总耦合元件的长度是一个谐振长度。The coupling element includes a portion that is mutually coupled to the first and second antenna elements and a portion that is not mutually coupled to the first and second antenna elements, the portion that is mutually coupled to the first and second antenna elements affects β, and The portion that is not mutually coupled with the first and second antenna elements is used to ensure that the total coupling element length is a resonant length.15.根据权利要求14所述的天线系统，其中所述天线系统包括一个二维（2D）阵列。15. The antenna system of claim 14, wherein said antenna system comprises a two-dimensional (2D) array.16.根据权利要求14所述的天线系统，其中所述天线系统包括一个三维（3D）阵列。16. The antenna system of claim 14, wherein said antenna system comprises a three-dimensional (3D) array.17.根据权利要求14所述的天线系统，其中所述第一和第二天线元件包括平面倒F型天线（PIFA）元件。17. The antenna system of claim 14, wherein the first and second antenna elements comprise planar inverted-F antenna (PIFA) elements.18.根据权利要求14所述的天线系统，其中所述第一和第二天线元件提供两个或多个单一运行频带，其中所述耦合元件在所述两个或多个单一运行频带上提供隔离。18. The antenna system according to claim 14, wherein said first and second antenna elements provide two or more single operating frequency bands, wherein said coupling element provides isolation.19.根据权利要求14所述的天线系统，其中所述天线系统包含在一个通用串行总线（USB）道尔芯片内。19. The antenna system of claim 14, wherein said antenna system is contained within a Universal Serial Bus (USB) dongle.20.根据权利要求19所述的天线系统，其中所述天线系统提供无线局域网（LAN）连接。20. The antenna system of claim 19, wherein the antenna system provides a wireless local area network (LAN) connection.

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